Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the burden. It discloses the exact kind of information returned (storage, extensions/MIME/spec, viewer availability, conversions), making behavior predictable. It doesn't mention handling of unknown formats, but the read-only nature is strongly implied by 'identify' and 'get how to open or convert it'.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tightly written sentences: the first states purpose and examples, the second lists the output contents and common use cases. No redundant words or filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a single-parameter identification tool, the description covers input forms and the output domain thoroughly. There is no output schema, so the description appropriately fills in return-value expectations. It could mention what happens for unknown formats, but that is a minor gap.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema already describes the single parameter as 'An extension, filename, or format slug' (100% coverage). The description adds concrete examples ('step', 'scan.mcap', 'gltf') and clarifies the accepted forms, adding value beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states a specific action ('Identify a file format') with input sources (extension, filename, slug) and detailed output contents. It also naturally distinguishes itself from siblings like convert_file and compare_formats.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explicitly tells the agent when to use it: 'Use for "what is this file" / "how do I open X".' It does not explicitly name alternatives or when-not-to-use, but the use-case guidance is clear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.